Commitments (Tables)
 12 Months Ended
Dec. 31, 2016
Commitments [Abstract]  
Minimum Annual Rental Commitments
Minimum annual rental commitments at December 31, 2016 under existing agreements are summarized as follows:

Year ending December 31
   
2017
 
$
4,213
 
2018
  
3,936
 
2019
  
3,565
 
2020
  
2,345
 
2021
  
3,777
 
Total
 
$
17,836